The invention relates to a tube connector for a pressure, tearout-resistant and positive high-pressure screw union. The screw union includes a deformed tube, a union member or connecting piece with a cone which is followed by an axially parallel bore with a radial end face, a union nut, a sealing ring and a retaining ring. The deformed tube has an end piece of the same tube diameter which is roughly axially parallel according to the depth of the tube seat bottom.
The invention, furthermore, relates to a process for making a complex tube deformation with the aid of a modified upsetting procedure, as well as tools for the implementation of the process.
Tube connections by means of tube deformation are known in a wide variety of embodiments, the realization of such deformations being effected mainly by means of upsetting operations, and the forming operation being limited for reasons of deformation-engineering and material. In particular, complex tube deformations cannot be realized with the known upsetting procedures.
A tube connector in which the tube to be formed is bulged out by inserting a metal ring as an abutment piece is known from the European Patent Application 0 380 970 A2. A clamping device with pressure areas cooperating with the abutment areas of the abutment piece is provided on the outer face of the tube. Such a tube connector is particularly suitable for plastic tubes and flexible hoses. It cannot, however, control high and maximum pressures.
A union for a flat-cone pressure line in which the connecting end is formed from the tube material is known from DD 240 059. A connecting shoulder pressed on according to the contours of a standardized cutting ring and a conical portion running out forwardly is formed in the region of the union of a pressure-line tube. Its cone angle is smaller than the cone angle of the conical opening of a standardized threaded connecting piece. In a large area of the union there are different inner tube diameters which also create different inner tube resistances for the flow medium. This known system does not offer receiving space for a seal.
DE 19511063 A1 describes a tube connector having a union member with cone and a union nut, with the tube deformation adapting itself largely, but not exactly, to the shape of the cone as well as the union nut. In one embodiment, the free space forming between the inclined surface of the union nut and the front face of the union member is filled up with a sealant. In a further embodiment, a sealing member is arranged between the conical surface of the union member and the deformed tube. When using a standardized union nut, a larger area of the conical surface remains unused. Likewise, the radial face of the connecting piece is not used or only insufficiently used in special cases so that transfer of the assembly forces onto the tube to be connected essentially takes place via inclined surfaces, resulting in the exclusive use of components of the forces applied. Moreover, completion of the assembling operation is conveyed indistinctly to the fitter so that overtightening seems to be possible.
DE 19520099 describes a tube connector for a pressure-tight and positive connection with a deformed tube, a union member with a cone which is followed by an axially parallel bore with a radial end face and a union nut, the deformed tube having an end piece of the same tube diameter which is axially parallel according to the depth of the tube seat bottom. In the assembled condition, a radially extending locating ring face of the deformed tube comes to rest against the front face of the tube connecting piece.
A further union with a supporting ring can be gathered from DE 19742917 C1 which relates to easily deformable and thin-walled tubes. The area of the deformed tube covered by the cone of the union nut is extremely small, while the larger part is covered by the supporting ring. It is true that this permits assembly on a block, but there is no certainty regarding the tearout resistance of the tube in high-pressure applications.
DE 195 41 622 A1 describes a high-pressure connection system with a cutting-ring connection and a connection with a deformed tube. The parts of the tube deformation form a maximum angle of 45° or less with the elements of the tube union so that only corresponding components of the applied assembly forces are transferred onto the tube. Assembly on a block is not possible so that completion of the assembling operation cannot be conveyed distinctly to the fitter and overtightening can take place very easily. In addition, the radial force components applied during assembly cause a constriction of the deformed tube region and its immediate vicinity. A constriction reduces the pretension of the upstream seal and, thus, the sealing behavior of the connection system. In addition, the constriction causes a reduction of the overlapping faces between tube deformation and union nut and, thus, a reduction of the tearout resistance.